Error Correction in GPS Signal

Methods and systems for correcting an error of a GPS signal are provided. The method includes receiving a request for positioning service from a computing device at a location; estimating a Total Electron Content (vTEC) value associated with the location of the object based at least in part on a plurality of vTEC values of a plurality of ground stations equipped with a plurality of GPS receivers, the vTEC value being estimated based on an estimator that is trained using a filter-reweight-retrain robust algorithm; and sending information of the estimated vTEC value to the computing device to allow the computing device to correct an error of a GPS signal received by the computing device, the error of the GPS signal being associated with an ionospheric delay.